Key Amino Acid for Life Discovered in a Stellar Cloud

The presence of the essential amino acid Tryptophan has been found in a stellar cloud IC348 located just 1000 light-years away from Earth
A captioned version of the Spitzer Telescope’s image of the Perseus molecular cloud. Credit: NASA

Astronomers have discovered high quantities of the amino acid tryptophan in a stellar cloud in a nearby region of space, only 1000 light-years away from us (ref.). Tryptophan is one of the 20 amino acids responsible for the formation of key proteins, even essential for life on Earth.

The fingerprints of this amino acid, in the form of unique spectral lines, have been identified in the data collected by the Spitzer Space Telescope in the IC348 star system. The discovery could indicate that the amino acids building proteins may be present in the gas and dust collapsing to form planetary systems around young stars.

IC348 stellar cloud

“The evidence of tryptophan in the molecular complex of Perseus should encourage further efforts to identify other amino acids in this region and in other regions of stellar formation” declared the scientist behind the discovery, Susana Iglesias-Groth, in a statement (ref.). “It is a very exciting possibility that the building blocks of proteins are widely present in the gas from which stars and planets form. It could be the key to the development of life in exoplanetary systems.”

IC348 is part of the Perseus Molecular Complex, a massive cloud of gas and dust containing material with a mass equivalent to 10,000 Suns. The gas cloud is estimated to be reasonably young in cosmic terms, only 2-3 million years old. Our Solar System is 4.5 billion years old.

IC348 is one of the closest star-forming regions to our planet. Although IC348 is usually invisible to the naked eye, the region shines brightly in infrared light. By analyzing these emissions, Iglesias-Groth found the 20 emission lines of the tryptophan molecule.

Molecular soup of IC348

Spectroscopic analysis reveals the chemical composition of molecular clouds, interstellar gas, stars, and planetary atmospheres. Different elements and chemical compounds absorb and emit light at unique wavelengths. This means that the spectrum is a kind of fingerprint that space telescopes can analyze. The discovered tryptophan is at a temperature of about 7°C.

Iglesias-Groth had previously used spectroscopy and Spitzer to detect other important biological precursors in the IC348 star system. In 2019, she discovered complex carbon molecules, carbon-60 fullerenes, which can act as building blocks for key life molecules.

Earlier this year, Iglesias-Groth discovered a “soup” of complex molecules in the star cluster, including molecular hydrogen, hydroxyl, water, carbon dioxide, and ammonia. In addition to several carbon-based molecules that could play a role in the formation of more complex hydrocarbons and prebiotic molecules, such as hydrogen cyanide, ethane, hexatriene, and benzene. “IC348 seems to be very rich and diverse in its molecular content” Iglesias-Gorth said in a statement earlier this year (ref.). “The novelty is that we see molecules in the diffuse gas from which stars and protoplanetary disks are forming”.

Deepening with the James Webb

The presence of prebiotic molecules in these gas and dust clouds means that young forming planets can accumulate these substances and potentially support the development of life. Alternatively, these molecules could be sealed in asteroids from the multiple impacts that occur during the turbulent early years of planetary systems.

Whatever the delivery mechanism, once on the planet’s surface, these molecules could engage in chemical processes that form proteins and eventually lead to the development of life. Iglesias-Groth now intends to continue research based on Spitzer with additional observations to be made with the James Webb Space Telescope.

“The spectroscopic capability of the James Webb could provide details on the spatial distribution of all these molecules. Extending this research to other more complex molecules, providing greater sensitivity and resolution essential to confirm the probable presence of this amino acid in this stellar cloud” Iglesias-Groth said earlier this year.

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